Technology
LCA: India's aeronautical industry at the cross-roads
Air Cmde RV Phadke

THE FIRST flight of the Light Combat Aircraft (LCA) prototype, more correctly, Technology Demonstrator or TD-1 on 4 Jan 2001 has gone down in India's aviation history as a landmark event. All those associated with the development of the LCA especially the scientists, engineers and others, deserve the nation's unreserved congratulations and felicitations.

But there will always remain a strong segment of informed opinion that will find it difficult to applaud this indigenous effort of the DRDO's subordinate organisation, the Aeronautical Development Agency (ADA), India's premier aerospace company HAL and last but not least the National Flight Test Centre.

Yet no one can deny that the much delayed flight of the LCA will give Indian scientists and engineers the long needed self-confidence to continue their efforts to operationalise the fledgling experimental technology demonstrator quickly, so it can enter operational service with the IAF on schedule. Inevitably, there will be many challenges before that happens and as in the past, the Doubting Thomas will take great pleasure in highlighting these problems.

  • Isn't the LCA already obsolescent?
  • Aren't we dependent on the US for the continued supply of the General Electric GE-F-404 engine? How can we get more of these if the sanctions remain in place? We are far from developing the multi-mode radar
  • Nor is there any sign of the indigenous Kaveri jet engine of the Gas Turbine Research Establishment (GTRE) Bangalore being available for some time
  • In any case, the LCA has only a limited range and payload since it was meant to replace the venerable MiG-21 fighter of the '50s vintage
  • The full authority quadruplex digital fly-by-wire flying control system also requires proving trials and debugging throughout the entire flight envelope, as do the myriad components of the aircraft
  • Integration of the various weapons and armaments and firing trials will also pose a major challenge as some of the missiles may come from Russia and the PGM from Western sources
  • It is also likely that the manufacturers of the hundreds of small but vital components will find it difficult to remain on the programme unless the major, and probably the only customer, the Indian Air Force places a firm demand on HAL for a sizeable number of the combat aircraft.

These and many other questions and doubts about the future of the LCA are indeed valid and some workable solutions would have to be found soon. Before we do that, however, we need to take a brief look at the history of India's aeronautics industry to understand and assess the chances of all these seemingly impossible tasks being performed in time and more importantly, to the satisfaction of the IAF because, in the ultimate analysis, it is the IAF that will employ the LCA in any future war.

What needs to be reiterated here is the fact that the future of the Indian Aeronautics Industry, especially HAL, is intricately linked to the future of the IAF. No modern state can hope to face the challenges of a newly globalizing and hence uncertain world without its modern air power being deeply rooted in indigenous aeronautical capability. HAL has a nearly 60-year long record of being the premier aerospace industry in South Asia. It produced the HT-2 piston engine trainer as far back as in 1951. It licence-produced a whole host of aircraft and helicopters of different types and pedigrees and was one of the first to design a contemporary fighter the HF-24 albeit with the help of a German designer Dr. Kurt Tank. The HF-24 first flew as early as June 1961 and despite the many teething problems, performed creditably in the 1971 Indo-Pak war. The lack of a suitable engine however put paid to its future and it was finally retired from the IAF in 1986.

The slow progress in the Kaveri engine may put similar stumbling blocks in the path of the LCA. The indigenously developed multi-mode radar with state-of-the-art capabilities is also likely to take time before it reaches production stage. A modern aircraft like tne LCA depends very largely on the airborne radar without which its agility and immense maneuvrability are of little value. Modern avionics, including the radar, are in fact the heart of a modern combat aircraft.

The LCA also has another unique feature in the form of a light-weight wing made of Carbon Fibre Composite (CFC) materials. Although the TD-1 & 2 wings were produced with the help of Alenia, an Italian company specialising in CFC technology, indications are that India has already developed this capability and will soon be able to produce the CFC wing without any further foreign support. It is reported that the ADA at Bangalore had funded and assisted some 180 Indian manufacturers to develop and fabricate the thousands of small parts of varying complexity that have gone into the LCA, and from all accounts they have done a commendable job.

It can thus be seen that continued progress of the LCA programme will impact on the future of many other fledgling and veteran programmes of the Indian aeronautics industry As is well known, India's space and missile programmes have shown remarkable progress in the last decade or so and there is every reason to believe that the spin-offs of their success will undoubtedly help the aeronautics industry. What needs to be remembered, however, is that unlike the missile which is a single shot or one-time use weapon, manned combat aircraft require a far higher reliability quotient. It is thus only natural that many glitches would have to be removed before the LCA is ready to enter operational squadron service, where it will be flown by relatively inexperienced pilots through the full flight envelope and not by a test pilot flying a predetermined profile. The flight of the TD-1, in that sense, was just the crossing of the first hurdle in a long marathon on an uneven road.

Coming back to the Kaveri, it is reported that the engine is ready to be flown on a flying test-bed in Russia. It is only after the successful completion of this crucial test that the development of this engine can move apace. The Kaveri is an ambitious project given that it will be a highly efficient engine of relatively small size but with a high thrust output. It is but natural, therefore, for those with experience in this field to doubt India's capability to successfully build such an engine in a short time. It is perhaps possible to say with the advantage of hindsight thatt India should never have abandoned her maiden venture to that was to design and produce an engine for the HF-24 aircraft. But let it be remembered that whenever India reached a decisive stage in indigenous development or manufacture of high technology components and aircraft, foreign manufacturers offered the same at very lucrative prices sometimes on repayment terms that a developing country, facing the threats that India did, could have ill-afforded to refuse. That is how international forces control the destinies of smaller players.

Today fortunately, India's economy and technology base is much more sound and the powers that be have learnt their lessons in self-reliance. In today's market driven world of MNCs where even giants of the aviation industry are merging with others to form even bigger business conglomerates, it is difficult for an inexperienced regional player like India's HAL to survive without some very clever and deft moves to remain afloat. HAL will hopefully be gainfully occupied in producing the 124 upgraded MiG-21 bis fighters, the 140 Su-30 MKI, a large number of Intermediate Jet Trainers as replacement for the nearly 30-year-old Kiran trainers, the Dornier, Alloutte and many other licence produced aircraft together with components and engines. HAL also has the task of overhauling the Mirage-2000 and the MiG-29 fighters.

It is in addition to these varied tasks that the HAL will have to produce the LCA prototypes and later possibly more aircraft on order. The crux of the argument is that without a demand for at least some 50 or 60 units of the LCA, it may be difticult for the HAL and indeed even DRDO-ADA to continue development work on this promising but challenging experiment. The IAF will no doubt support the programme but whether or not it can allocate the necessary funds every year for the projected notional demand of some 50/60 aircraft is doubtful, at least at the present moment. This is simply because there is no guarantee that HAL will indeed produce the numbers ordered on schedule.

To be fair, it is too early for HAL to make a commitment to complete the production of even 20 aircraft by a definite date since the LCA is far from a proven platform and it will be at least five years before the picture starts to become clear. The IFC or Initial Flight Clearance is planned only for 2005 and FFC or Full Flight Clearance for 2010. There is also the fear of the aircraft becoming obsolete before it reaches squadron service. Given its state-of-the-art design, however, this fear is misplaced. In any case, it should be possible to upgrade the systems as the programme develops. Its 300 km ROA and some 8 ton armament payload do appear to be well short of its contemporaries. But then a light combat aircraft to be used essentially for air defence and strike cannot be expected to carry the same payloads as the Su-30 which is in a different class altogether.

The IAF cannot obviously wait indefinitely for equipping some four to six of its frontline squadrons with this indigenous fighter, however promising it may be, simply because like any air arm the IAF has to forever remain ready to successfully fight a war that may erupt tomorrow. No Air Chief can ever ignore that primary responsibility. Given the induction of high-tech weapons systems in India's neighbourhood, the Air Chief is indeed in an unenviable position. This is the Catch-22 situation that one would hope never to get into. Neither the development of the LCA nor the short-term defence needs of the nation can be ignored. The only possible option could be a compromise at the least possible cost.

Considering that the Kaveri engine and the multi-mode radar are the two major components without which the LCA cannot ever see squadron service, India could hunt for a foreign engine and radar as an interim measure. The Russian built RD-33 presently fitted on the MiG-29 is being upgraded to RD-93 for single engine use. (The MiG-29 has two RD-33 engines) The French M-88-2/3 an engine fitted on the Rafale is also in the same class and may be available. Both these engines have nearly the same dimensions and thrust rating as the GE F-404 and who knows, with the change of guard at the White House, sanctions may be lifted even earlier and a suitable engine like the P&W F-100 or GE110 (presently fitted on the F-16 CIDs) may be available from the USA.

There are two possible candidates for the multi-mode radar, the Israeli ELTA EL/M-20022 or the Russian Phazatron Kopyo. The former is the better of the two but the latter is being fitted on the upgraded MiG-21 bis aircraft and it may be easier and even economical to get some 50 additional pieces from Moscow, provided of course the IAF accepts the arrangement. It can be hoped that with the likely addition of sizeable numbers of Su-30 MKIs and even some Mirage-2000 aircraft and the already upgraded MiG-21s and MiG-27s, it might not be too difficult to convince the IAF. This is where HAL, DRDO and indeed the Ministry of Defence will have to play a constructive role and give forecasts that are genuine and realistic or else the IAF will once again feel let down.

In the past too, it was not for lack of understanding of the problems of a nascent aeronautics industry that the IAF appeared to shop for foreign aircraft, but mainly because the production schedules were not strictly adhered to. As is well known, any indigenous aircraft industry must first win the confidence of the nation's air force and only then can it expect the air force to support it. There are many examples of the most highly advanced combat aircraft not being accepted for export untill that country's air force first inducted them.

In the circumstances, it seems that the IAF would do well to support the development of the LCA with a firm order for some 50 aircraft, but only after the developers and the producers provide a realistic schedule. It would not be fair to allow the former to exercise a veto every time the latter wants some new equipment because finally when the chips are down, it is the IAF that has to defend the nation's airspace. There are no runners-up in this game. Unless India's decision-makers collectively assist and promote it, the KH-2001 may remain just a costly technology demonstrator.

The author is a Senior Fellow at the Institute of Defence Studies & Analysis

(c) Indian Defence Review

Editor's Note: The article is interesting when seen in the light of reports that Russia has offered to help develop the LCA. The offer was made at the recently concluded AeroIndia show in Bangalore by aircraft makers MiG and Sukhoi. Russia's Air Force Chief General Anatoly Kornukov, who was in Delhi briefly before flying to Bangalore, is reported to have discussed the issue with India's Air Chief Yeshwant Tipnis and Defence Secretary Yogendra Narain. He was later quoted by The Times of India as saying: "I have certain things to propose but I don't want to make these details public." Russia is not entirely new to the LCA programme. The indigenously developed Kaveri engine is undergoing extensive trials in Russia and is now expected to be flight tested on a Russian TU16 aircraft. Defence Minister George Fernandes has welcomed Russia's offer to help productionise the LCA but said his ministry is also exploring the possibility of involving some South-east Asian countries in the programme in an attempt to share costs.

The Russian offer lends weight to Air Commodore Phadke's argument that whenever India was close to a breakthrough in areas of defence technology, foreign consortiums would step in with offers to sell the same at considerably reduced rates. In the process, Indian industry and engineers lost out. But until details of the Russian offer are known, it would not be fair to attribute motives to them.

It's been suggested that the Russians may have recommended modifications to the Kaveri. Such modification may require the assent of the US since the Kaveri is based on the GE 404 engine technology. Developing an entirely new engine for the LCA could delay it even further. Besides, Russian involvement in the LCA deepens India's dependence on Russian technology and equipment. Barring the Mirage and Jaguars, Russian fighters form the backbone of the IAF (124 MiG 21Bis now being upgraded, 165 MiG 27s and 74 MiG 29s also due for upgrade and the proposed acquisition of around 28 MiG 29Ks for the Indian Navy). However, it's also true that Russia has gone far beyond LCA technology and would not find it difficult to develop something appropriate quickly.

It could also be that Russia's proposal maybe intended to open the doors for the possible sale of the MiG Advanced Trainer. The trainer was on show at AeroIndia and Russian representatives have hinted at producing it in India. The delay in the acquisition of the Hawk AJT, because of India's insistence that it have no American components, has added to rumours that the deal may fall through. Reports from Moscow have quoted unnamed sources as claiming that the AJT deal is in fact off (which is not the case). Ironically, the LCA was the first major US involvement in such a high profile Indian defence programme. The agreement signed with Lockheed Martin in 1988 envisaged that company developing the flight control systems. If things had proceeded smoothly, the LCA would have been powered by technology equivalent to the earlier variants of the F 16. Unfortunately, US sanctions put paid to that. The recent US lifting of sanctions on the sale of spares for the Indian Navy's Seaking helicopters has revived hopes of a change in their attitude to the LCA programme also.

Dreams lighten in LCA
Sqn. Ldr. B.G. Prakash


THE INITIAL design of the LCA was based on a metallic body, but ambitious men wanted to use composites. The Indian Air Force opted for a metallic fuselage with traditional technology instead of experimenting with unproven composites. After all, only about half a dozen countries around the world, Italy's Aliena, Germany, France's Mirage and Air Bus, Britain's British Aerospace and Jaguar - are well versed with handling composite technology. The US depends on its very advanced metal technology and less on composites, though about 45 per cent of the F-22 Raptor aircraft comprises of composites.

Advanced composite units at NAL and HAL were established. Both have been instrumental in supporting HANSA, SARAS and the LCA. Prahlad says that bridging a technological gap - as in handling the composites - is more important than satisfying the design aspects. Assemblies with fasteners, bolts, rivets get replaced by monolithic composite components. The spin off is easily absorbable in space launch vehicles and guided missiles, where reusability and pilot's lives are not issues.

Significant Achievement


The use of composites results in a 40 per cent reduction in the total number of parts: For instance, 3,000 parts in a metallic design would come down to 1,800 parts in a composite design. The number of fasteners has been reduced to half in the composite structure from 10,000 in the metallic frame. The composite design helped to avoid about 2,000 holes being drilled into the airframe. Though the weight comes down by 21 per cent, the most interesting prediction is the time it will take to assemble the LCA -- the airframe that takes 11 months to build can be done in seven months using composites.

Involvement of British Aerospace

A component that has curvature, bend and sharp edges may look easy to be formed with composites. But its strength and stress-bearing capacity at certain points is difficult to measure and to improve upon. Tooling design is the most critical requirement in composite technology. The skin of the LCA measures 3 mm at its thickest with the average thickness varying between 2.4 to 2.7 mm. The skin needs to bear a force of 100 Newton per mm. What the designers initially achieved was just 40 N/mm. With some improvements it reached 60 N/mm. Interaction with BAe offered some solutions. BAe is reported to have achieved 160 to 180 N/mm which was a challenge. It came to light only later that they were working with skin thickness of 6 mm. This was a lesson well learnt when composites were used in the bulkhead and stiffener underneath the skin.

T - Pull

The T-Pull problem was another headache for the designers. T-pull occurs at skin and stiffener edge. It includes two forces: One force which acts perpendicular to a surface is referred to as 'sigma z'. The inter-lamination shear stress the trme to assemble the LCA - the airframe that takes along the surface is the other. The flat top of a T-joint meshes with the surface of a composite panel. Adhesives hold them together. The 'leg' of the T joins the flat top not in a perfect mesh - but creates a triangular void at the junction. This is termed as the Bermuda Triangle. Forces tend to pull the leg away from the top; the initial design could withstand only 40 N/mm. An innovative introduction of a thin composite interface strip between the flat top of T and the surface improved the strength dramatically to 60 N/mm. From a basic design scheme it graduated into padded configuration and overlay configuration. Failure was expected at the joints - which did not happen.

On the fuel tank floor, horizontal and longitudinal stiffeners cross each other. At the point of crossing, the longitudinal members are cut out to allow the breadth-wise members to pass through. This process is intricate and special tooling was necessary. Stiffeners join the surface in T-joint and need to be perpendicular to the surface - at exactly 90 degrees!

Research and analysis are continuing to make the T-joint stronger. Adhesives and reinforcement are used to fill the void. Flex cores are used which not only look simple but also elegant. Stitches to bind the flat top of the T to the surface is another method. The recommendations of BAe helped and further progress is foreseen. A 'duct dividing wall' made of composites, which reduces the number of parts and fasteners, is another indigenous effort. It was conceived against existing norms. Complex tool is developed to work on an area measuring 3 m by 1 5 m made of composite. Baffle frame stiffener in fuel tank needs precision engineering.

Air Duct

The Air Duct is a monolithic piece that needs stiffeners. Generally stiffeners protrude outward or inward depending on the component. But the surface of air duct is to be smooth and protrusion of stiffeners cannot be outward lest it obstruct free airflow. So stiffeners are embedded and internal. According to Simha the consultant, one of the 'two best parts' designed is used where the air duct enters the fuselage, with four external and two internal stiffeners, which replaces nearly 30 metallic components. A conventional design could have been used. In the conventional sandwich design, two thin skins called face sheets of 0.3 mm to 1.5 mm thickness are separated by honeycomb struts made of aramid based nomex. The separated space of 10 mm to 20 mm is mostly hollow. Sandwich panels are used in under carriage door, hatches or panel covering the armament bay. Repeated failure was encountered at the inner skin of the air intake with the sandwich design, using metal or composite adopted until then. The other best part is the Y-joint in the floor of the fuel tank with longitudinal stiffeners along the body.

Y - Joint

The Y-Joint is an innovation in the airframe of the LCA where the air duct joins the floor of the fuel tank. Centre fuselage holds the fuel tank which is 2.5 m long. This part needs to handle hook stress and bending stress with the skin being 2.4 mm thick. A monolithic composite part that replaces several metallic pieces was developed. It merges with a counterpart at the bottom, which contains the fuel tank floor. Prevention of fuel leakage is of prime importance. Simha conceived of a small extension at the edge of the top piece, in a new design, which had to mesh with a similar receptacle in the bottom part in a Y-shaped joint. One arm of the Y runs to a length of 1.75 m along the fuel tank floor. No one was sure that it could be manufactured to required specifications. NAL helped. With stiffeners both inside and on the external surface, the secondary bonding technique was successfully used to a length of 1.75 m. The scientist who made this says: "One learns from nature. Branches of trees join the trunk usually in a Y-joint. It must be naturally strong."

Fin and Torque Shaft

The fin for the LCA is a monolithic honeycomb piece. No other manufacturer is known to have made fins out of a single piece. The torque shaft for actuating the rudder is a challenge. It is built on additive process. The cost of manufacture reduces by 80 per cent from Rs 2.5 million in this process. This is contrary to a subtractive or deductive method normally adopted in advanced countries, when the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. A 'nose' for the rudder is added by 'squeeze' riveting.

LCA has hats

Yet another innovative design is stiffener of hat section. It has a cross-section that resembles a hat in sequences, it endured the tests and worked well. A honeycomb sandwich piece measuring 400 mm in breadth was not reflecting the required strength to withstand shear forces. Other manufacturers have used similar designs. Within the breadth of 400 mm a hat like cross-section, six or seven in number, successively linked in sequence in the stiffener, is tried in the design. In fact about 30 per cent of the composite material is carved out from the original strip. Hollow portions are created. Yet the design proved capable of withstanding larger shearing forces. It is an optimisation of shape. Engineers use Finite Element Analysis in optimising. FEA computer software are available. Now, an engineer can develop new software based on this design. Autolay -- the software used by designers in the project -- is fondly mentioned.

Section 5435 and 8385

Composites are used in the inner skin at air intake on section 5435 of the front fuselage, at section 8385 of the rear fuselage and at the external skin of rear fuselage. The policy statement stipulates that small cutouts in the airframe are to be minimised; only large cut outs for access are acceptable. Where the straight stiffeners did not provide the required strength, flanged reinforcements were successfully tried. Benefits accrued in achieving improved buckling factor and consequently effected manageable stress concentration.

Lightning Strikes

When lightning strikes the LCA, four metal longerons stretching from end to end, afford protection. In addition, all the panels are provided with copper mesh. One out of five is 'bonding' bolt with gaskets to handle Electr-Magnetic Interference. Aluminum foils cover bolt heads while the fuel tank is taken care of with isolation and grounding.

Corrugated Composite and Test

Some components are of sheets that taper down from a thickness of 9 mm to 3 mm. Obviously, the lamination should dwindle without losing strength. A corrugated finish, which is meticulously achieved, is used. NAL has the only Non-Destructive Test facility in India using ultrasonic tests with frequency varying from 1 to 10 megahertz to test composites. It is needed at many stages in development. Result is in the form of colour images and is analyzed.

Indian Institute of Technology, Powai is involved in providing test boxes, which replace a few test panels. Ultrasonic based testing is necessary on composite surface, which does not show cracks but can have de-laminated layers. Dent shows up on composites though the design allows for barely visible damage to the skin, which may not grow. Moisture is absorbed by composite but the design takes this into consideration. A portable ultrasonic test gear is under development, which can be used in field formations.

SARAS is Thinner

The passenger aircraft under development, SARAS, has control surface that uses composite sheet of 0.6 mm thickness. Squeeze riveting used here is more sophisticated. Technology usable on a sheet with 3 mm thickness cannot be directly adopted.

Appropriate Technology

Plaster of paris is used to make moulds on which composite sheets of the required thickness including the taper are shaped. Surface of the mould needs to be absolutely plane, which is provided by smoothly machined granite tabletops on the workbench. Templates support the plaster block on both sides. The compound solidifies by normal sunlight. To prevent shrinking, solidifying compound from losing its surface grip on the template, screw and nut are inserted on the template. The nut acts as locking nut. Depending on the complexity, the number of screw holes increase. Appropriate technology is in use in the most sophisticated aircraft that this country has seen.

From a level of non-use, composites now form nearly half of the airframe, which carries 30 per cent of the total weight of the aircraft. At times, wealth of information gets poverty of attention - more so with the LCA. May the will of each Indian fly with it!

(c) Indian Defence Review

 

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No. 0015/ Issue: February 16, 2001